Bhagavad Gita
Chapter 15 · Verse 7
ममैवांशो जीवलोके जीवभूतः सनातनः। मनःषष्ठानीन्द्रियाणि प्रकृतिस्थानि कर्षति॥
mamaivāṁśo jīva-loke jīva-bhūtaḥ sanātanaḥ, manaḥ-ṣaṣṭhānīndriyāṇi prakṛti-sthāni karṣati
A description of the self as something eternal at the core, temporarily working through the mind and senses like tools it has taken up.
Something eternal lives at the center of you, wearing the mind and senses like a garment.